CTLA-4基因多态性调节溃疡性结肠炎患者CTLA-4 mRNA稳定性和蛋白水平  

CTLA-4 gene polymorphism regulates CTLA-4 mRNA stability and protein level in patients with ulcerative colitis

作　　者：陈志涛[1] 夏冰[1] 姜挺[1] 周峰[1] 邹开芳[2] 葛柳青[1] 

机构地区：[1]武汉大学中南医院消化内科、湖北省医学肠病临床研究中心、湖北省过敏与免疫相关疾病重点实验室,430071 [2]华中科技大学同济医学院附属协和医院消化内科

出　　处：《中华医学遗传学杂志》2010年第6期603-609,共7页Chinese Journal of Medical Genetics

基　　金：国家自然科学基金（30871149）

摘　　要：目的 研究细胞毒T淋巴细胞相关抗原4（cytotoxic T-lymphocyte associated antigen 4,CTLA-4）基因3＇非转录区（AT）n重复序列多态性对溃疡性结肠炎（ulcerative colitis,UC）患者CTLA-4mRNA稳定性和基因表达的影响.方法 采用实时定量PCR方法检测膜型CTLA-4（full length CTLA-4,flCTLA-4）和可溶性CTLA-4（soluble CTLA-4,sCTLA-4）mRNA表达,半衰期法分析其mRNA稳定性.免疫组化检测flCTLA-4蛋白表达.酶联免疫吸附实验测定sCTLA-4蛋白水平.荧光PCR-毛细管电泳技术检测300例UC患者和700名健康对照者CTLA-4基因（AT）n重复序列多态性.结果 活动期UC患者肠黏膜sCTLA-4 mRNA的表达显著低于缓解期UC患者（P=0.004）.在UC患者中,（AT）n重复序列长等位基因携带者表达低水平的flCTLA-4和sCTLA-4 mRNA以及sCTLA-4蛋白（均P＜0.01）.携带长等位基因的UC患者CTLA-4 mRNA的稳定性明显降低.UC患者CTLA-4基因（AT）n重复序列长等位基因携带者（≥116 bp）频率显著高于正常对照组（P＜0.01）,且与广泛型结肠炎相关（P=0.008）.结论 UC患者CTLA-4基因（AT）n重复序列多态性与CTLA-4基因表达水平相关,携带（AT）n重复序列长等位基因的UC患者CTLA-4 mRNA及蛋白的表达降低,提示CTLA-4基因在UC遗传免疫发病机制中起重要作用.Objective To investigate the effect of （AT）n repeat polymorphism of the 3＇untranslated region in cytotoxic T-lymphocyte associated antigen 4 （CTLA-4）gene on CTLA-4 mRNA stability and full length （flCTLA-4） and soluble CTLA4 （sCTLA-4） expression in ulcerative colitis （UC）. Methods flCTLA-4 mRNA in colonic biopsies and sCTLA-4 mRNA stability in peripheral blood mononuclear cells of UC patients were measured by quantitative PCR and half-life, respectively. The protein expression of flCTLA-4 in colonic biopsies and sCTLA-4 in sera of UC patients were determined by immunohistochemistry and enzyme-linked immunosorbent assay, respectively. The polymorphism of CTLA-4 （AT）n repeats in 300 UC and 700 age and sex matched healthy controls was genotyped by fluorescent PCR. Results Among the UC patients, sCTLA-4 mRNA expression levels were decreased in active disease compared to non-active disease （P=0. 004）. Carriers of the longer alleles of the （AT）n repeats expressed lower levels of flCTLA-4 and sCTLA - 4 mRNA and sCTLA - 4 protein than those of the shorter alleles in UC （all P〈0.01）, and mRNA with long （AT）n repeat alleles has shorter half-life than mRNA with short alleles and, hence, are unstable. The frequency of long allele carriers of CTLA-4 （AT）n repeats was significantly higher in UC patients than in the healthy controls （22.0% vs. 6.3%, P〈0.01, OR=4.21, 95% CI： 2.79-6.33）, and associated with extensive colitis （P=0. 008）. Conclusion CTLA-4 gene expression levels were associated with （AT）n repeat polymorphisms in UC patients. The expression of CTLA-4 mRNA and protein were decreased in carriers of the longer alleles of the （AT）n repeats of CTLA-4 gene. This study suggests that CTLA-4 plays an important role in genetic risk and pathophysiology for UC in central China.

关 键 词：细胞毒T淋巴细胞相关抗原4 溃疡性结肠炎 (AT)n重复序列 遗传多态性 表达 

分 类 号：R686[医药卫生—骨科学]